A conventionally proposed plug of the type described above is, for example, a power supply plug having a structure in which a core wire of an electric line is connected to a base portion of a terminal and a tip end of the electric line and the base portion of the terminal are covered with a vinyl chloride resin so that the electric line and the terminal are integrated together (see Patent Document 1). Such a power supply plug has an electric line wiring structure in which the core wire exposed from the tip end of the electric line is connected to the base portion of the terminal by caulking or soldering.
However, such a power supply plug may be pulled out of a power supply such as, for example, an electric outlet, without being held by hand; namely, the electric line connected to the power supply plug may be pulled by hand. There are also cases where a human, an animal, a cart, a trolley or the like may be caught by the electric line, resulting in the power supply plug being forcibly pulled out.
When the power supply plug is pulled out in a manner described above, a tensile load is applied to the electric line. This tensile load is directly applied to a connection portion of the electric line and the terminal. Therefore, for example, delamination or line breakage easily occurs on the connection portion of the electric line and the terminal. This causes a problem that the electric connection cannot be maintained.